DESCRIPTION: (Taken from project abstract) Repetitive DNA represents over 50% of eukaryotic genomes and contains a tremendous wealth of information about genomic structure and evolution. Its knowledge is of crucial importance for understanding complex relationships between genetic blueprints and their biological functions. It is also of practical significance for genome mapping and sequencing projects. Inevitably, researchers studying growing numbers of DNA sequences in the coming years will have to analyze increasing numbers of repetitive elements integrated within them in ever growing detail. There are at least three major aspects of such studies: (I) automatic annotation of repetitive DNA using reference collections of sequences of known repeats and specialized computer software; (ii) evaluation of particular repeats based on the existing biological information, and (iii) other specialized studies involving sequence context and properties of the repeats. Such studies will require electronically available and constantly updated database containing reference collections of repeats, description of the reference repeats organized in a condensed form, and specialized collections allowing detailed studies of available homologous repeats. The first database of repetitive DNA known as "Repbase" has been released by our group in 1992. Here we propose further steps necessary to improve and enhance this resource. Our specific goals include: 1. Develop and maintain reference collections of repetitive elements from all sequenced eukaryotic species. 2. Initiate a peer-reviewed electronic encyclopedia containing, updated key information on repetitive DNA. 3. Develop and maintain secondary collections of repetitive DNA.